This invention relates generally to medical devices and more particularly to ultrasonic angioplasty catheters for effecting ultrasonic ablation of occlusive intravascular lesions.
Ultrasound transmitting catheters have been utilized to successfully ablate various types of obstructions from blood vessels of humans and animals. Additionally, ultrasound transmitting catheters may be utilized to deliver ultrasonic energy to mammalian blood vessels for the purpose of preventing or reversing vasospasm, as described in U.S. Pat. No. 5,324,255 (Passafaro, et al.).
Particular success has been observed in ablation of atherosclerotic plaque or thromboembolic obstructions from peripheral blood vessels such as the femoral arteries. Successful applications of ultrasonic energy to smaller blood vessels, such as the coronary arteries, necessitates the use of ultrasound transmitting catheters which are sufficiently small and flexible to permit transluminal advancement of such catheters through the tortuous vasculature of the aortic arch and coronary tree. Accordingly, the safety and efficacy of removing obstructions from coronary arteries by way of ultrasound is largely dependent upon the size and flexibility of the ultrasound transmitting catheter(s) employed.
One particular type of ultrasound transmitting catheter which may be utilized to deliver therapeutic ultrasound to an intracorporeal treatment site comprises an elongate flexible catheter body having rigid distal tip or head member inserted into, and affixed thereto with at least one ultrasound transmission member extending longitudinally through the catheter body being coupled to the distal tip or head member, as described in U.S. Pat. No. 5,542,917 (Nita, et al.).
Although these devices are of merit, there still exists a need in the art for further invention, development and refinement of the previously known ultrasound catheters to provide catheters with improved maneuverability for advancing through the small and tight tortuous blood vessels, such as the coronaries arteries.
The present invention is directed to a catheter style for shaping an ultrasound catheter for delivering ultrasonic energy to a treatment location within a patient""s body. The stylet of the present invention has proximal and distal portions with a distal end. The stylet distal end is sufficiently larger than a distal passage aperture of the ultrasound delivery catheter to maintain the stylet distal end within the ultrasound delivery catheter body at the distal end of the ultrasound delivery catheter. Additionally, the stylet has sufficient stiffness to bring about the desired deflection at the catheter distal end to negotiate the catheter through tortuous anatomy during treatment. Preferably, the distal end of the stylet has a predetermined shape, preferably in the shape of a curve to bring about the desired deflection at the distal end of the ultrasound delivery catheter.
In one embodiment, the stylet comprises an elongate core member having proximal and distal portions with a distal end. Additionally, a flexible body having a distal end is disposed about a section of the elongate core member distal portion. The flexible body is secured to the elongate core member a point proximal to the elongate core member distal end. The flexible body, may further include a plug at the distal end thereof. The plug has is sufficiently larger than a distal aperture of the catheter such that the distal end of the stylet is kept within the catheter body at the distal end of the catheter during treatment.
In operation, the stylet is inserted into the catheter body (before or after the catheter body has been inserted into the patient""s body). The stylet is moved longitudinally within and with respect to the catheter body to bring about a desired deflection at the catheter distal end, allowing the catheter to be negotiated through tortuous anatomy. Thereafter, the stylet is removed from the catheter.